Manufacture of filaments and films from viscose



' elasticity,

.that the cellulose hydrate lulose hydrate products by Patented Mar. 1,192

UNITED STATES v 1,576,531 PATENT OFFICE.

WILLIAM MENDEL, OF BEVERLY, NEW JERSEY.

manurao'ruan or rlrmnnrs AND FILMS FROM vrscosn.

No Drawing. Original application filed April 29, 1925, Serial No.26,825. Divided and this application filed April 29, 1925.

To all whom it'mag concern.

Be it known that I, WILLIAM Murmur, a citizen of the United States,residing at Beverly, in the county of Burlington and State of NewJersey, have invented a certain new and useful Improvement, in theManufacture of Filaments and Films from Viscose, whereof the followingis a specification. I

This is a division of my copending application Serial No. 26,825, filedApril 29, 1925, and. the invention herein claimed includes methods andmeans. for chemically purifying cellulose products which are primarilyformed by conversion of liquid viscose (cellulose sulphocarbonate) tocoagulated or precipitated cellulose complex. Viscose has a strongtendency to progressive decomposition with reversion of the cellulose toits insoluble and uncombined condition, and such reversion isfacilitated and may be effected by the mere'action'ofheatwithout theemployment of chemicals, and my invention is applicable to filaments andfilms thus formed. y It is characteristic of all such products .is notin a pure state but mixed with free sul hur and its derivatives, forinstance, su phides, sulphites, sulphates and thiosulphates. Some ofsuch impurities are soluble, but others are insoluble and increasinglydifiicult to remove, in accordance with the thickness of the filament orfilm. Sulphur and its derivatives in such roducts, detract from all ofthe qualities w ich make the latter vauable, especially their luster,strength and and the presence of such deleteriousmatter is manifested bythe opacity of the product and the dullness of its appearance.

Heretofore, attempts have been made to remove such impurities bytreatment of such products with sulphites and sulphides, particularlythe latter, and by theuse of reducers such as bisulphite orformaldehyde, and oxidizers such as bleaching powder, permanganate ofpotash or sodium; peroxide. However, the action of such materials isincomplete and extremely slow' and, consequently, unsatisfactory.

I have discovered that such sulphurous impurities may be eliminated fromsuch celreaction of trisodium phosphate (Na,PO,) therewith; as

other; subjecting them to the Serial NO. 26,827.

such reaction converts the sulphur to soluble poly-sulphides andthio-sulphates. Therefore, my invention consists in the use of suchrcageutto effect the removal of such sulphurous impurities from suchproducts.

My invention is advantageously employed in the manufacture oftransparent and translucent films in extensive sheets and webs, whichmay be coagulated by heat upon drums, plates, or other suitable carriersand then subjected to the action of the tri-sodium phosphate.

Although the purification and clarification herein contemplated areeffected mostrapidly when the cellulose hydrate products are submergedin a hot saturated aqueous solution of tri-sodium phosphate; such asolution quickly becomes clogged with the soluble products of thereaction. Therefore, I find it preferable to use dilute solutionsbecause, although a longer time is required,

the desired result is more economically attained, but it is to beunderstood that trisodium phosphate is efficient for the purposecontemplated at'any temperature and in any state of dilution.

The action of fected with great rapidity. For instance, such a film .025inch thick, of a dull yel lowish-white chalky appearance; when boiledfor two minutes in a saturated aqueous solution of tri-sodium phosphatebecomes .almost as clear and transparent as glass and, when dried, formsa websuperior in transparency, strength and elasticity to others of thatsize which have been subjected to the action of ordinary reagents for amuch longer time. Of course, the reaction in accordance with myinvention is more rapid with filaments of less. thickness.

Therefore, I find it preferable to utilize my invention as follows: Inorder that the reagent may uniformly affect the films, I wind the latteron suitable drums; then mount the drumson an ordinary dye jigger andwind thefilm' from one drum to the action of a three per cent aqueoussolution of tri-sodium phosp ate; preferably boiling for about tenminutes, more or less, depending on the thickness of the film.Thereafter, such sulphur bearing impurities which have been renderedsoluble may be readily removed from the residual cellulose hydrate ofthe films, by merely rinsing the latter in water.

my invention may be ef- The films may then be dried, preferably againsta polished surface and without further chemical treatment excel inbrilliance, luster and elasticity and are perfectly clear andtransparent, their luster being determined by the nature of the surfaceagainst which they have been dried, which may be more or less smooth orembody a pattern.

Although I have described what I con-- sider a preferable method ofcarrying out,

my invention; I do not desire'to limit myself to the precise details ofconstruction, arrangement or procedure herein set forth, as it isobvious that various modifications may be made therein without departingfrom the essential features of my invention, as defined in the appendedclaims.

Specific claims for other processes wherein such products have beenprimarily formed in baths which include suitable acid, or salt, arerespectively included in other applications for Letters Patent of theUnited States copending herewith.

I claim:

1. The process of manufacturing articles from viscose by precipitatingsuch viscose by heat, and subjecting the same to the action oftri-sodium hosphate (Na POQ.

2. The process 0 manufacturing articles from viscose by precipitatingsuch viscose by heat, and subjecting the same to the action oftri-sodium phosphate (Na PO,), in aqueous solution.

3. The process of manufacturing films and webs from viscose whichincludes solidifying su'ch viscose in such forms, byheat, and treatingthe resultant product with tri-sodium phosphate in aqueous solution.

4. The method of eliminating sulphur and its derivatives residual in aviscose product which has been converted to cellulose hydrate by heat,by subjecting said product to the action of tri-sodium phosphate inaqueous solution, and redrying it.

5. The method of eliminating sulphur and its derivatives residual in aproduct formed by the action of heat on viscose, by intermittentlysubjecting said product to the action of tri-sodium phosphate in aqueoussolution.

6. The process of treating viscose which has been subjected to asolidifying process, by heat, which consists in subjecting such productto the action of trisodium phosphate before finally drying it.

. In testimony whereof, I have hereunto signed my name at Burlington,New Jersey, this twenty-seventh day of April, 1925.

' WILLIAM MENDEL.

